It should then be re applied at least every two hours, as the protective filters can break down over time.
至少每隔两小时要补一次防晒，因为保护物质会慢慢分解。
The Anglo-French company rushed to fix the problem it said caused several of its trains to break down: powdery snow that seeped through protective filters and triggered a major engine malfunction.
这家英法合资公司一直在抓紧时间解决问题。公司说，导致几辆列车瘫痪的原因是：粉状降雪渗透到保护过滤器中，引发引擎出现了严重故障。
Protective countermeasures are under development, including lens shutters and filters that block certain laser frequencies.
防御性对策正在开发，包括透镜光闸及滤波器，能阻止某个频谱的激光。
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